1. Technical Field of the Invention
The present invention pertains in general to dispatch systems and cellular telephone networks, and more particularly, to a method and apparatus for deploying a dispatch system using group lists and standard radiotelephone networks.
2. Description of Related Art
The use of cellular telephones has increased dramatically in the past several years and demand for cellular telephone service is expected to continue growing into the future. The radio frequency spectrum used by cellular telephone networks and other wireless services, however, is a limited resource. There is a need, therefore, to utilize the radio frequency spectrum as efficiently as possible. While the various cellular telephone network standards have evolved into increasingly more efficient approaches to using the radio frequency spectrum, other wireless services which share the radio frequency spectrum with the cellular telephone networks have not. One such group of wireless services comprises dispatch systems commonly used by mobile fleets such as taxis and delivery trucks.
Dispatch systems generally comprise a single dispatch center communicating with multiple mobile units (e.g., taxis or trucks) using radios. This "point-to-multipoint" communication is usually half duplex as only the dispatch center or one of the mobile units can transmit at any given time. This is in contrast to the full duplex and "point-to-point" communication of cellular telephone networks. Frequently, the radio spectrum allotted to a dispatch system provides capacity in excess of what is actually needed by the dispatch service. Furthermore, during non-peak times, few transmissions occur and the allotted radio frequency remains under utilized.
Radio frequency bands used by dispatch systems sometimes occupy portions of the radio frequency spectrum which could be used to provide cellular telephone service. Use of the radio frequency band allocated to dispatch services for cellular telephone service would provide communication for a greater number of individuals, provide more efficient use of a limited resource, and increase the communication capacity of the radio frequency band. Before the radio frequency band can be reallocated for use by cellular telephone networks, however, a method of communication must be provided to the users of the displaced dispatch system. Systems have been developed which address the issue of group calls associated with dispatch systems in cellular telephone networks. However, none have disclosed a method or apparatus for providing a dispatch system in a cellular telephone network using current cellular telephone network standards and requiring no special equipment. It would be advantageous, therefore, to devise a method and apparatus using a cellular telephone network to provide dispatch communication capabilities consistent with the point-to-multipoint nature of current dispatch systems.